This invention relates to the fixing of shaped bodies to metal casting moulds for the purpose of identification.
Our U.S. Pat. No. 3,934,639, describes and claims a method of marking an ingot which comprises locating an indicia-defining body on one or more faces of the interior of an ingot mould prior to casting molten metal into the mould. The indicia-defining bodies are each formed of a foam plastics substrate having bonded refractory material throughout (i.e. on and in) its structure and may be fixed to the ingot mould wall by a variety of techniques, for example, by nails fired from suitable guns and by adhesives.
Various types of adhesives have been proposed. However, they all fail to meet the stringent requirement of always operating satisfactorily despite the various conditions of use of the ingot mould. In practice the condition of the mould wall varies greatly; the wall can be smooth and relatively clean or it may be dirty, badly fissured or coated with a mould dressing. It is not practical to require the steel worker to pre-clean the area of the ingot mould wall where the indicia-defining bodies are to be fixed since this is too expensive and time consuming. Furthermore, the mould wall temperature may very greatly, e.g. from about 20.degree. C to more than 250.degree. C.
Certain two-pack adhesives are available but these can only be mixed on site in view of their limited shelf life once mixed. Such adhesives are therefore inconvenient and they are also expensive. It is also known to use a contact adhesive in conjunction with a layer of vulcanisable rubber. While this system can provide adequate adhesive properties for some conditions of use it does not have adequate adhesive properties under all conditions of use, and its application to the indicia-defining bodies during their manufacture can be too time consuming.
It is possible to pretreat the mould wall with a primer to consolidate loose surface material and cause it to adhere to the sound metal of the mould. However, while the use of a primer can reduce the demands on the adhesive, this again involves an additional operation which is labour intensive and expensive. Furthermore, primer compositions are usually disadvantageous in that they can evolve poisonous or inflammable vapours.
According to the present invention there is provided a method of fixing a shaped body of refractory material to an interior face of an ingot mould, which method comprises applying to either the body or the face or both a mixture consisting essentially of aqueous alkali metal silicate and a particulate refractory material, the mixture having a viscosity of at least 2000 poises measured on a Brookfield Viscometer model RVT at 20.degree. C, and urging together the body and the face.